Improvements furnaces



H. M. SMITH.

Furnace. No. 167,579, Patented Sept. 7,1875.

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error HORATIO M. SMITH, OF CHICAGO, ILLINOIS.

IMPROVEMENT IN FURNACES.

Specification forming part of Letters Patent No. 1167,5379, datedSeptember '7, 1875; application filed July 8, 1875.

OAsE D.

To all whom it may concern Be it known that I, HORATIO M. SMITH, ofChicago, in the county of Cook and State of Illinois, have inventedcertain Improvements in Furnaces for the combustion of coal; and Ihereby declare that the following is a full, clear, and exactdescription of the same, which, taken in connection with theaccompanying drawing, that forms a part of this specification, will besufficient to enable those skilled in the art to make and use theinvention.

The drawing shows at Figure 1 a front exterior View of the furnace; atFig. 2 a vertical section on w a". of Fig. 1, and at Fig. 3 a verticalsection on the plane y Like letters of reference made use of in theseveral figures indicate like parts wherever used.

It is well known that bituminous coals are rich in combustible matters,which volatilize at a comparatively low temperature and that in theordinary modes of combustion these volatile constituents become mostlywaste products of combustion, which pass out of the furnace in the formof smoke and invisible carbonic compounds. It is also well understoodthat sufficient air cannot pass through the grate to produce completecombustion of the necessary quantity of coal resting thereon, and thoughan accelerated draft intensifies combustion and proportionately elevatesthe temperature, yet it is equally well known that the fires cannot beurged beyond a certain point except at an expense of fuel greater inproportion than the increase of temperature obtained. Therefore theproblem has been to burn these combustible gases after they have beendistilled and escaped from the coal upon the grate. Active combustioncannot occur below a certain temperature, and from the moment ofliberation these gases begin to lose heat, and the admission of cold airabove the grate may, and generally does, cool them below the temperatureof ignition.

The object of this invention is to effect the complete combustion ofthese gases by subjectingthem totheintenseheat of ablastwithoutaccelerating the draft through the grate. It is evident this efi'ectshould be produced as near to the grate as possible.

My invention, therefore, relates to that class of furnaces calledsmoke-consuming; and it consists, first, in a narrow throat at the rearend of the grate, through which these 'waste gases, mixed with freshair, may be compelled to pass at an accelerated velocity, and in contactwith a mass of intensely-burning fuel, whereby the temperature is soraised that combustion is made complete; second, in a, dead-platecontinuation of the grate-surface to hold the coke or coal which is usedto block up said archway; third, in a splayed or inclined bridge-wallbehind said arch and dead-plate to permit the flame to be partlydifl'used before impinging upon the boiler.

I am aware that many furnaces have been constructed wherein the wastegases and smoke have been compelled to pass the flame of a second fire;but in this furnace one part of the same fire is maintained at a muchhigher temperature than the remainder, and the waste gases are compelledto pass said hot part before they have lost temperature or formedincombustible oxides.

In the said drawing, A represents a steamboiler of ordinary style. B Bare the exterior walls of the furnace. G is a central verticaldivision-wall extending from the ground up to the boiler, and from thefront back to the in clined bridge-wall. D is the inclined bridgewall,made in this form so that the draft of flame will not be caused toimpinge too abruptly upon the boiler, to avoid the danger of burning theboiler out at a certain point. Within each of the two chambers E E,formed by the exterior walls, the boiler, and the central wall, areplaced partition-arches F, at a pointjust over, or very near to, thefear end of the grate G, and in front of the inclined bridge-wall D.These arches descend nearly to the grate G, so near that a narrow throatis formed, which may be readily blocked ,up with the fuel, and whichwill be so narrow that no gases can pass through without being heated tothe required degree to insure combustion if a suflicient quantity of airshould be present. An air'vent, f, is placed at this arch, debouchingeither downward at the crown of the arch, as shown, or to the side orfront over the arch, to insure a proper supply of air. I call the partsF arches, because they are such in the furnace illustrated, and I preferthat they should be arches in form; but it is not essential that theyshould have this form. as will be readily understood. Nor is itessential that they should be placed in the precise position shown, asit may often be advisable to put them farther back, even beyond the backof the grate. In front of the arches F, and above the grate, beingnearly upon a -level therewith, is the archway or passage H, forming acommunication between the chambers E and E. The doorsJ are provided withregulable draft-openings j, and similar openings o'furnish an air-supplyby suitable conduits 7a, which deliver it into the chambers E E at ornear the rear, and also into the arched passage H from above, as shown.

It is not desirable that the coal or coke pushed under the arch F, toblock up the same, should rest against the bridge-wall D, because thedraft would thereby be detrimentally obstructed; and I therefore extendthe dead-plate t backward on a level with the grate sufficiently far toform a base for the pile of fuel which chokes said arch, and from therear end of said dead-plate the bridge wall D rises with an inclinationbackward, which permits the flame to become somewhat diffused beforeimpinging upon the boiler, and therefore there is no danger of burningthe latter in the vicinity of the bridge-wall.

In working this improved furnace I first charge both chambers with coal,and dam up the fuel at the arches F, so that it shall become coked; or,if preferred, coke-tires may be built in each chamber, or a coke-firemay be built upon one side and a coal-fire upon the other. When fairlystarted in the latter case, I dam up the coal under the arch F bypushing it back, so that there shall be very little or no draft out overthe bridge-wall. Sometimes it may be found desirable to close thisoutlet by the damper K. The draft is thus brought around through thepassage H into the other chamber containing a coke-fire. Air from theapertures at the rear and at the passage H mingles with the gasesevolved from the coal, both at the time of their generation and as theypass through the passage H, and the said gases should, therefore, bein acondition to burn upon entering the chamber containing the coke-fire.The flame is carried, by the draft in the latter chamber, up over thebridge-wall in the usual manner.

The two chambers are alike, as will be noticed, and when the coal in theclosed chamber has become reduced to coke, a charge of coal is placed inthe outer chamber in like manner and dammed up at the throat under thearch F, making it in turn a coking-chamber, and the draft is reversedinto the other chamber; or, if desired, the coke may be dumped by thegrate and transferred from one chamber to the other, via the ash-pit.

The top of both chambers is formed by the boiler, so that all of theheat generated within the chambers is felt upon the boiler.

A single chamber provided with the closelydescending arch F may besuccessfully, and with good effect, used; but I prefer two, asdescribed, for the reasons indicated.

In cases where furnaces have but one door the central verticaldivision-wall C may be brought to the front or to within a shortdistance of it, so that the gases may pass from the coking to thecombustion chamber around the front edge of the wall 0.

In many instances where the draft is good, and the grate andsteam-heating surfaces are plenty, it will not be necessary to bank thecoke under the throat on either side, as the small space left betweenthe arch F and the grate-surface, through which the mingled' smoke andair must pass, will force them so near the incandescent coke or coals asto insure combustion in the chamber Where the gases are generated.

What I claim as new is 1. In a furnace, the. combination, with the ifcombined with the bridge-wall D, for the purpose described.

HORATIO M. SMITH.

Witnesses:

JOHN W. MUNDAY, Enw. S. EVARTS.

